As Long Term Evolution (LTE) wireless networks are being deployed to more places around the world, user equipment (UE) need to support an increasing number of LTE frequency division duplexing (FDD) frequency bands and time division duplexing (TDD) frequency bands. FDD operation uses a pair of frequency bands, one for communication in the uplink direction from the UE to a wireless network and one for communication in the downlink direction from the wireless network to the UE. TDD operation uses a single frequency band for communication in both the uplink and downlink directions. LTE wireless communication protocols specify different LTE frequency bands for FDD and TDD operation. The UE determines whether an FDD transmission or a TDD transmission can be made on a given frequency band. There are a large number of different frequency bands allocated for FDD LTE use, in which pairs of FDD LTE frequency bands can be associated together for simultaneous transmission in the uplink and downlink directions. Additionally, there are several different frequency bands allocated for TDD LTE use. With an increasing number of FDD and TDD LTE frequency bands available for use by a UE, there is a need to accelerate the LTE cell selection and reselection process.
Release 10 of the Third Generation Partnership Project (3GPP) LTE wireless communication protocol specification introduced carrier aggregation (CA) to provide for wider bandwidths for use by a UE. Carrier aggregation increases available bandwidth delivered to a UE by using multiple frequency bands with multiple carriers in parallel. Two or more component carriers (CCs) can be aggregated together to form a larger overall bandwidth for communication, e.g., up to 100 MHz of bandwidth by aggregating five different 20 MHz wide frequency bands. Carrier aggregation further allows for radio frequency spectrum deployment of component carriers that are contiguous or non-contiguous. Carrier aggregation of contiguous CCs within the same operating frequency band, as provided for LTE, is referred to as intra-band contiguous aggregation. Carrier aggregation of non-contiguous CCs that belong to the same frequency band with one or more gaps between the CCs is referred to as intra-band non-contiguous aggregation. Additionally, inter-band, non-contiguous carrier aggregation uses CCs that belong to different frequency bands. Each component carrier can support a frequency bandwidth of 1.4, 3, 5, 10, 15 or 20 MHz, which can vary for different component carriers. Component carriers are associated with a serving cell. In LTE Release 10, a maximum of five component carriers can be combined, and each component carrier can be associated with an independent receive signaling path in a UE.
Carrier aggregation can be used by a UE while in an LTE connected mode to communicate through multiple frequency bands in parallel to increase downlink (DL) and/or uplink (UL) data rates. Carrier aggregation is not used by the UE while in an LTE idle mode. LTE idle mode procedures can include actions such as cell measurement, cell search, cell selection, and cell reselection. Cell measurement includes measuring signal quality and signal strength of neighbor cells, while cell search includes locating a cell on which to camp. Cell selection includes determining a particular cell from a set of candidate cells, while cell reselection includes determining to switch from an existing cell to another cell. Each of these LTE idle mode procedures can be time consuming, which affects availability of a service for a user of the UE, and consumes limited battery power while being performed. Therefore, what is desired is a method to accelerate cell search and measurement by a mobile wireless device.